Having submitted evidence that localized tissue production of prostaglandins may be responsible for certain manifestations of periodontal disease, that prostaglandin inhibitors will inhibit gingival prostaglandin synthesis and that prostaglandin antagonist will inhibit prostaglandin stimulated bone resorption it is proposed that the latter findings be further clarified. For the purpose of screening drugs of the PG-synthetase inhibitor class for their ability to block gingival PG production, a gingival microsome preparation will be made. For the purpose of screening drugs of the PG-antagonist class for their ability to block PG mediated bone resorption, work will be extended with an invitro bone tissue culture assay. A study of the effects of a variety of compounds in these two systems will provide information needed to determine the best agents to test in therapy and suggest the possibility of developing drugs which effective by both mechanisms of action. Collaborative investigations on the genesis of prostaglandins through antigen-antibody reaction and complement will provide needed information on the conditions under which PG's are produced.